Method of bleaching barytes



and allied industries.

I Patented Apr. 14, 1925 UNITED STATES" PATENT- OFFICE.-

WILLIS r. wasmsunu, or s'r, LOUIS, mssoum, Assrcivon'ro'unriouar rremnnrs &

, CHEMICAL COMPANY, or $17. tours; MISSOURI, A CORPORATION or mssoum.

mnrnon or 'BLEACHILNG ,BARY'TES;

No Drawing;

To all whom it may concern:

Be it known that I, WILLIS F. WAsnnURN,

a citizen of the Uni-ted States, and residing at St. Louis, State of Missouri, have invented the new and useful Improvement in Methods of Bleaching Baryte's, of which thefollovving is a specification.

This inventiomrelates to the art of bleacl1- ing barytes, and more particularly to render .it suitable for use in the In the art of bleaching'barytes as heretofore practiced, the crude material is crushed to suitable size and 'Washed until free from clay and other adhering impurities, It is then placed in suitable mills, usually of the ball or tube type and reduced to the desired fineness. The fine material is then placed in a suitablecontainer and acid (usually so]- phuric acid) added and the mixture is boiled until a sample shows that the desired degree of bleaching'has'been attained. The action of the acid is to leach out the impurities which are usually present in the form oi oxides of iron, manganese, etc, some of which are diflicultly soluble in acid, and some of which may not be completely soluble. The time required is, therefore, not only extendedand not only is the amount of acid required considerable, but the result may not be a product of the desired color.

One of the objects of this invention, therefore, is to develop a method or processof bleaching in which the time required is not only reduced but in which the resulting 'product is of a superior color.

Further objects will appear from the'detail description in which an embodiment of this invention will be described; it wil however, be understood that the invention may be exei'nplified in other embodiments.

I have discovered that it a reducing agent is present in the mixture during, the blcacln much less'time is required for the operation and that the resulting product is of superior color. There are many reducing agents which may be used for this purpose, for example, stannous and titanous salts, the metals which react with acid with liberation of hydrogen, electrolysis, etc: an agent especially suitable and convenient for this purpose is metallic iron.

enerally stated in accordance with this invention the barytes is treated with a suitable acid in the presence of av reducing agent,

paint, rubber, color Application filed April 28, 1924. Serial Nb. 709,652;

such as hydrogen.v This hydrogen is pref I erably liberated by the .action of an agent, such as described. Where a-metal is used, it is preferably such that its salt is soluble; and'where iron is used, it is preferably one which is low in carbon, such as Wrought iron.

The acid used is preferably sulphuric acid, although other acids, such as hydro-chloric acid maybe used. Y I

As a practical embodiment of this invention, the process or method may be carried out asfollows: Crude barytes is crushed to about 1-inch mesh, washed .with Water and wet ground in a tube mill to a suitable fineness, such as250 mesh, and water floated to,

eliminate any coarse particles; The resulting finely dividedbarytes, usually in the form I of a slurry containing 10 to percent water is pumped into a suitable tank and sulphuric acid' added. The amount of acid used may be varied considerably, from 1 to 4 tons Be. acid to 30 tons of slurry has been found to be. satisfactory. There is then introduced into the treating tank a suitable quantity of metallic iron, such as wrought iron, which for convenience may be in the'form of bars. The amount of iron required depends upon the impurities originally present in the barytes and may be'readily determined by trial. The mixture is then boiled bythe inof the desiredcolor. The bleached barytes is then washed and dried.

As a result of the improved method or process not only is the resulting product of a superior color, but much less time is required for the operation in order to secure that result.- The action is probably due to the reduction of the difticultly soluble or in soluble oxides crother impurities to the more ited to the specific details described.

Having thus described the invention, What is claimed is:

It. A method oi: bleaci'im r .1

-arytes consist jection of live steam until the barytes is till ing in treating the barytes with a mineral acid in the presence of a gaseous reducing agent.

2. A method of bleaching barytes consisting in treating the barytes with a mineral acid in the presence of hydrogen.

3. A method of bleaching barytes consisting in treating the barytes with a mineral acid in the presence of an agent which reacts with the acid with liberation of hydrogen.

4. A method of bleaching barytes consisting in'treating the barytes with a. mineral acid in the presence of a metal which reacts with the acid with liberation of hydrogen.

'ing in treating the barytes wit acid in the presence of a metal whose salt is 5. A method of bleaching bar es consistsoluble.

U. A method of bleaching barytes consisting in treating the barytes with a mineral acid in the presence of metallic iron.

7. A method of bleaching barytes consisting in treating the barytes with sulphuric acid in the presence of low carbon iron.

In testimony whereof I aflix my signature this 5th day of April, 1924.

WILLIS F. WASHBURN.

a mineral 

